When patients are being mechanically ventilated on an intensive-care ward, for example, the patient to be ventilated is connected pneumatically to the ventilator or respirator by a system of ventilation tubing. Because the breathing air delivered to the patient must be adjusted with respect to temperature and humidity to meet the physiological needs of the patient, a respiratory humidifier or respiratory humidifier is arranged in the inhalation or inspiration tube to heat and humidify the breathing air. The respiratory humidifier comprises a liquid container filled with distilled water, through which the breathing air is conducted and humidified.
The heating of the liquid in the liquid container is usually accomplished by means of a heating plate in the bottom part of the housing of the respiratory humidifier, wherein the heat is transferred from the heating plate to the thermally conductive bottom of the liquid container. The temperature of the breathing air is measured by suitable sensors as it flows in and out, for example, and evaluated so that the respiratory humidifier can be controlled appropriately.
To avoid that the liquid container runs dry or becomes filled with too much liquid, the level of liquid in the container is monitored.
Because, for hygienic reasons, the system of breathing air tubing and the liquid container are designed as medical-grade single-use or disposable articles, two different functional portions are used in a respiratory humidifier. First is the stationary housing, which is connected to the power supply and possibly to other medical devices over a data line; second is the replaceable liquid container, which is usually delivered with the inhalation tubes already attached, so that there is as little chance as possible that the nursing personnel will connect them incorrectly.
The housing and the liquid container must be connected solidly together during operation. In particular, it is absolutely necessary to have good thermal contact between the bottom plate of the liquid container and the heating plate of the housing to ensure adequate heat transfer.
Known respiratory humidifiers with integrated liquid containers, such as that described in US 2006/0113690 A1, also comprise user interfaces, which inform the user about the functional parameters of the respiratory humidifier, for example; and they also have appropriate elements for controlling the operation of the respiratory humidifier. These user interfaces are usually arranged either vertically or horizontally, however, so that they can be seen and operated essentially only from the front or from above. In some cases, they are arranged underneath the liquid container, which means that it is awkward to access them to read or adjust the settings.
Another arrangement of a liquid container in a respiratory humidifier is described in U.S. Pat. No. 4,715,998.
Another disadvantage of the known respiratory humidifiers is that they are relatively large and awkwardly shaped with many corners and edges, for example. They also comprise a large number of connections and contain complicated structural elements. Such devices are therefore complicated to operate, subject to malfunction, and expensive to acquire.
It is therefore the object of the present invention to provide a respiratory humidifier which overcomes the disadvantages cited above and which in particular comprises a user interface which can be operated from the front as well as from above; is simple, ergonomic, and compact in design; and reliably fulfills many different functions.
This object is achieved by the features of claim 1. Advantageous designs and embodiments are described in the subclaims.